#!/usr/bin/python3
###############################################################################
# BRLTTY - A background process providing access to the console screen (when in
#          text mode) for a blind person using a refreshable braille display.
#
# Copyright (C) 1995-2021 by The BRLTTY Developers.
#
# BRLTTY comes with ABSOLUTELY NO WARRANTY.
#
# This is free software, placed under the terms of the
# GNU Lesser General Public License, as published by the Free Software
# Foundation; either version 2.1 of the License, or (at your option) any
# later version. Please see the file LICENSE-LGPL for details.
#
# Web Page: http://brltty.app/
#
# This software is maintained by Dave Mielke <dave@mielke.cc>.
###############################################################################

# BRLTTY Contraction Table - latex-access (executable)

import sys, os

def putProgramMessage (message):
  stream = sys.stderr
  stream.write(os.path.basename(sys.argv[0]) + ": " + message + "\n")
  stream.flush()

def syntaxError (message):
  putProgramMessage(message)
  exit(2)

def semanticError (message):
  putProgramMessage(message)
  exit(3)

def systemError (message):
  putProgramMessage(message)
  exit(4)

def missingPackage (name):
  systemError("package not installed: " + name)

def putResponseProperty (keyword, value):
  value = unicode(value)
  if programArguments.verbose: putProgramMessage("rsp: " + keyword + "=" + value)

  stream = sys.stdout
  stream.write(keyword + "=" + value.encode("UTF-8") + "\n")
  stream.flush()

def getRequest ():
  request = {}

  while True:
    try:
      if programArguments.interactive:
        line = raw_input(packageName + "> ")
      else:
        line = raw_input()
    except EOFError:
      if len(request) == 0: return None
      semanticError("unexpected end-of-file on standard input")

    line = line.decode("UTF-8")
    components = line.split("=", 1)

    if len(components) > 1:
      (keyword, value) = components
      keyword = keyword.strip().lower()

      if programArguments.verbose: putProgramMessage("req: " + keyword + "=" + value)
      request[keyword] = value
      if keyword == "text": break

  return request

def processRequest ():
  request = getRequest()
  if not request: return False

  for attribute in ("displayLength", "cursorOffset", "expandCurrentWord", "consumedChars"):
    if hasattr(brailleTranslator, attribute):
      delattr(brailleTranslator, attribute)

  if request.has_key("maximum-length"):
    brailleTranslator.displayLength = int(request["maximum-length"])

  if request.has_key("cursor-position"):
    position = int(request["cursor-position"])

    if position > 0:
      brailleTranslator.cursorOffset = position - 1

      if request.has_key("expand-current-word"):
        brailleTranslator.expandCurrentWord = int(request["expand-current-word"]) != 0

  brailleTranslator.capitalisation = "6dot"
  if request.has_key("capitalization-mode"):
    if int(request["capitalization-mode"]) != 1:
      brailleTranslator.capitalisation = "8dot"

  text = request["text"]
  brf = brailleTranslator.translate(textPreprocessor.translate(text))

  if hasattr(brailleTranslator, "consumedChars"):
    consumedLength = brailleTranslator.consumedChars
    putResponseProperty("consumed-length", consumedLength)
  else:
    consumedLength = len(text)

  if hasattr(brailleTranslator, "src2trans"):
    offsets = brailleTranslator.src2trans
    if len(offsets) > consumedLength: offsets = offsets[:consumedLength]
    putResponseProperty("output-offsets", ",".join((str(offset) for offset in offsets)))

  putResponseProperty("brf", brf)
  return True

def parseProgramArguments ():
  import argparse
  parser = argparse.ArgumentParser(
    prog = os.path.basename(sys.argv[0]),
    usage = "%(prog)s [option ...]",
    description = """
      This is an executable contraction table for BRLTTY
      that uses the latex-access package
      to translate LaTeX mathematical notation into braille.
      BRLTTY can be found at [http://brltty.app/].
      latex-access can be found at [http://www.latex-access.sourceforge.net/].
    """
  )

  parser.add_argument(
    "-c", "--configuration",
    action = "store",
    nargs = 1,
    dest = "configuration",
    default = (
      os.path.join(os.path.expanduser("~"), "." + packageName),
      "/etc/" + packageName + ".conf"
    ),
    help = "the configuration file to use"
  )

  parser.add_argument(
    "-n", "--nemeth",
    action = "store_const",
    const = "nemeth",
    dest = "translator",
    help = "translate into Nemeth Code"
  )

  parser.add_argument(
    "-u", "--ueb",
    action = "store_const",
    const = "ueb",
    dest = "translator",
    help = "translate into Unified English Braille"
  )

  parser.add_argument(
    "-i", "--interactive",
    action = "store_true",
    dest = "interactive",
    help = "enable input editing and history"
  )

  parser.add_argument(
    "-v", "--verbose",
    action = "store_true",
    dest = "verbose",
    help = "show request and response properties on standard error"
  )

  return parser.parse_args()

if __name__ == "__main__":
  packageName = "latex-access"

  programArguments = parseProgramArguments()

  if programArguments.interactive:
    import readline, atexit
    historyFile=os.path.join(os.path.expanduser("~"), "." + packageName + ".history")
    atexit.register(readline.write_history_file, historyFile)
    readline.read_history_file(historyFile)

  try:
    from latex_access import nemeth, ueb, preprocessor, settings
  except ImportError:
    missingPackage(packageName)

  for configurationFile in programArguments.configuration:
    if os.path.exists(configurationFile):
      if programArguments.verbose:
        putProgramMessage("configuration file: " + configurationFile)

      settings.loadSettings(configurationFile)
      break

  if programArguments.translator:
    settings.settings["brailletable"] = programArguments.translator

  brailleTranslator = settings.brailleTableToUse()
  textPreprocessor = preprocessor.preprocessor()

  settings.activateSettings(
    {
      "braille": brailleTranslator,
      "preprocessor": textPreprocessor
    }
  )

  while processRequest(): pass

